Hi Rc,
The G-90 has never quit running in the air or on the ground and I have always ran it a little rich like you say a smoke trail. It would even do the high then go to low idle speed on the test bench same as in the plane. I wanted to think that it was maybe just needed breaking in more like you said. I think i may have fixed it per my last message at least it didn't drop as many RPM's on idle as it did before. My tach is in the mail so I didn't get the exact numbers but before it would idle slow enough for my VF 66" Extra 300 to sit still and idle nice except for the weed eater sound, then after maybe a min. it would drop enough RPM that it would just run with alot of shaking. So when I am on approach and have the needles pegged to say running at about 1/4 throttle the RPM will drop then im adding power and when over the numbers im hot because the RPM's are still high. It seems to only do it at 1/4 throttle or less. It would be ok if i had a 5000' runway for some nice wheel landings but not that lucky. I hope to fly her later this week to see if I did any good on the test bench with alot of great advice from everyone here.